It is the long-range purpose of this project to study the perinatal development of the functioning small intestine in normal and environmentally-, nutritionally- and hormonally-stressed animals. The topics of present interest which relate to the development of the normal functioning small intestine are: (1) effect of prenatal exposure to hydrocortisone, hydrazine and dimethylhydrazine (DMH) on the development of enzymic indicators of membrane integrity and function, e.g., alkaline phosphatase, acid phosphatase, Na, K-ATPase, lactase and sucrase; (2) role of cell specificity in the susceptibility to the TCDD induction of UDP-glucuronyl transferase in intestinal crypt and tip cells in vivo and in vitro; (3) determination of the characteristic isozyme profile for Beta-glucuronidase during development and after DMH treatment as a possible indicator of toxicity and a precancerous state; (4) examination of intestinal membrane and serum marker enzyme development after prenatal exposure to polychlorinated biphenyl structural analogues; (5) relative contribution of the tip and crypt cells to energy metabolism of these cells; (6) mechanism of As-induced toxicity of mitochondrial function in normal and diabetic animals and (7) application of the isolated cells technique to metabolic and toxicologic problems. BIBLIOGRAPHIC REFERENCES: Fowler, B. A., Woods, J. S., and Schiller, C. M.: The ultrastructural and biochemical effects of prolonged oral arsenic exposure on liver mitochondria of rats. Environ. Health Perspec. 19: August, 1977. Schiller, C. M., Fowler, B. A., and Woods, J. S.: Arsenic effects on pyruvate dehydrogenase activation. Environ. Health Perspec. 19: August, 1977.